300+ REAL TIME Class 12 Biology Objective Questions & Answers 2023

250+ TOP MCQs on Ecosystem – Decomposition and Answers

Biology MCQs for Pharmacy Entrance Exams on “Ecosystem – Decomposition – 2”.

1. Along with oxygen what are the other components decomposition depend on?
a) Oxygen
b) Chemical composition of detritus
c) Decomposers
d) Leaching
Answer: b
Clarification: The physical and chemical process of break down complex organic remains (dead or decaying organisms) into inorganic substances is called decomposition. Along with the availability of oxygen, the decomposition also depends on the chemical composition of detritus.

2. Along with oxygen what are the other components decomposition depend on?
a) Climatic conditions
b) Decomposers
c) Humification
d) Leaching
Answer: a
Clarification: The physical and chemical process of break down complex organic remains (dead or decaying organisms) into inorganic substances is called decomposition. Along with the availability of oxygen, the decomposition also depends on the climatic conditions.

3. At what rate does decomposition occur when detritus is rich in nitrogen and sugars?
a) Slower
b) Faster
c) Moderate
d) Neutral
Answer: b
Clarification: When detritus is rich in nitrogen and sugars, the decomposition occurs at a faster rate. The physical and chemical process of break down complex organic remains (dead or decaying organisms) into inorganic substances is called decomposition.

4. At what rate does decomposition occur when detritus is rich in lignin and chitin?
a) Faster
b) Neutral
c) Moderate
d) Slower
Answer: d
Clarification: When detritus is rich in lignin and chitin the decomposition occurs at a slower rate. The physical and chemical process of break down complex organic remains (dead or decaying organisms) into inorganic substances is called decomposition.

5. What environment is favorable for the process of decomposition?
a) Low temperature and anaerobic conditions
b) High temperature
c) Warm and moist
d) Watery
Answer: c
Clarification: The physical and chemical process of break down complex organic remains (dead or decaying organisms) into inorganic substances is called decomposition. It is favored by a warm and moist environment.

6. What environment is unfavorable for the process of decomposition?
a) Warm
b) Low temperature and anaerobic conditions
c) Moist
d) Having good humus
Answer: b
Clarification: The physical and chemical process of break down complex organic remains (dead or decaying organisms) into inorganic substances is called decomposition. Low temperature and anaerobic conditions are unfavorable for the process of decomposition.

To practice Biology MCQs for Pharmacy Entrance Exams,

250+ TOP MCQs on Ecosystem Services and Answers Quiz

Biology Multiple Choice Questions on “Ecosystem Services”.

1. What is the base for economic, environmental and aesthetic goods and services?
a) Unhealthy ecosystem
b) Healthy ecosystem
c) Bad ecosystem
d) Convergent ecosystem

Answer: b
Clarification: The organizational level before biomes and after the population is called an ecosystem. An ecosystem consists of biotic and abiotic components that interact within a system. The base for economic, environmental and aesthetic goods and services is a healthy ecosystem.

2. What are the products of ecosystem processes named?
a) Ecological services
b) Ecological succession
c) Ecological issues
d) Ecological cycle

Answer: a
Clarification: Ecological services are said to be the products of ecosystem processes. The purified air and water, nutrients cycles, generation of fertile soil, providing habitat, maintaining biodiversity, providing storage sites for various minerals, etc. are the services provided by the healthy forest ecosystems.

3. Which of the following ecosystem helps in the pollination of crops?
a) Unfit ecosystem
b) Healthy ecosystem
c) Bad ecosystem
d) Unhealthy ecosystem

Answer: b
Clarification: The healthy forest ecosystems help in the pollination of crops. It is the ecological service that is the product of ecosystem processes. Healthy ecosystems also provide aesthetic, cultural and spiritual values.

4. Who has very recently tried to put price tags on nature’s life-support services?
a) Rudolf Virchow and his colleagues
b) Gregor Mendel and his colleagues
c) Robert Brown and his colleagues
d) Robert Constanza and his colleagues

Answer: d
Clarification: Ecological services are said to be the products of ecosystem processes. It is thought that biodiversity carries a hefty price tag. The action of putting price tags on nature’s life-support services was recently done by Robert Constanza and his colleagues.

5. According to the researchers, what is the average price tag of these fundamental ecosystem services?
a) US $ 300 trillion a year
b) US $ 33 trillion a year
c) US $ 5 trillion a year
d) US $ 1000 trillion a year

Answer: c
Clarification: Ecological services are said to be the products of ecosystem processes. It is thought that biodiversity carries a hefty price tag. According to the researchers, the average price tag of these fundamental ecosystem services is the US $ 33 trillion a year.

6. Why are the fundamental ecosystems services largely taken for granted?
a) Because they are expensive
b) Because they are free
c) Because they are exploited
d) Because they are highly-priced

Answer: b
Clarification: Ecological services are said to be the products of ecosystem processes. The base for economic, environmental and aesthetic goods and services is a healthy ecosystem. Since these services are free they are highly taken for granted.

7. Out of the total cost of various ecosystem services, how much is the cost of the soil formation?
a) 2 percent
b) 90 percent
c) 70 percent
d) 50 percent

Answer: d
Clarification: Ecological services are said to be the products of ecosystem processes. It is thought that biodiversity carries a hefty price tag. Out of the total cost of various ecosystem services, a 50 percent cost is required for soil formation.

8. Out of the total cost of various ecosystem services, how much is the cost of recreation and nutrient cycling?
a) 50 %
b) 88 %
c) > 10 %
d) < 20 %

Answer: c
Clarification: Ecological services are said to be the products of ecosystem processes. It is thought that biodiversity carries a hefty price tag. Out of the total cost of various ecosystem services, less than 10 percent is the cost of recreation and nutrient cycling.

9. Out of the total cost of various ecosystem services, how much is the cost of climate regulation and habitat for wildlife?
a) 20 % each
b) 10 % each
c) 50 % each
d) 6 % each

10. Which of the following are ecological services?
a) O₂ fixation, CO₂ release, and pollution
b) Nitrogen fixation and pollution
c) CO₂ fixation, O₂ release, and pollination
d) CO₂ fixation, fertilization, and the release of sodium

Answer: c
Clarification: Ecological services are said to be the products of ecosystem processes. The base for economic, environmental and aesthetic goods and services is a healthy ecosystem. CO₂ fixation, O₂ release, and pollination are some of them.

11. How do green plants fix CO₂?
a) Respiration
b) Photosynthesis
c) Fertilization
d) Pollination

Answer: b
Clarification: Photosynthesis is a process in which producers (green plants) in the presence of CO₂, water, sunlight, and chlorophyll yield energy and oxygen is released in the form of gas. The green plants utilize atmospheric CO₂ and release O₂ which is utilized by other organisms.

12. What is released as a byproduct of photosynthesis?
a) CO₂
b) NH₄
c) O₂
d) H₂

Answer: c
Clarification: Photosynthesis is a process in which producers (green plants) in the presence of CO₂, water, sunlight, and chlorophyll yield energy and oxygen is released in the form of gas. The green plants utilize atmospheric CO₂ and release O₂ which is utilized by other organisms.

13. Which of the following statement is correct about pollination?
a) The wind is not an agent of pollination
b) Insects can’t pollinate
c) Fruit formation occurs after pollination
d) Fertilization occurs before pollination

Answer: b
Clarification: The act of transfer of pollen grains from the male (part) anther to a female part (stigma) of a plant is known as pollination. After successful pollination, the process of fertilization occurs which leads to the formation of fruits and seeds.

14. Which of the following shows a one-way passage in an ecosystem?
a) Potassium
b) Carbon
c) Phosphorous
d) Free energy

Answer: d
Clarification: The movement of energy from the higher trophic levels and its distribution and loss as heat to the lower trophic levels in the environment is unidirectional. It means the energy moves in one direction only that is from higher to the lower-most level.

15. Whose work is to protect the land from floods, remove sediments and other pollutants and recharge groundwater?
a) Wetlands
b) Oceans
c) Rivers
d) Forests

Answer: a
Clarification: The formation of the wetland is a part of ecosystem service. Wetland is a type of ecosystem that is covered by water. The wetlands protect the land from floods, helps in the removal of sediments and other pollutants and recharge the groundwater.

16. Which of the following statement is incorrect?
a) Forest ecosystem helps in gaseous balance
b) Forest ecosystem helps in pollination
c) Forest ecosystem leads to the extinction of all organisms
d) Forest ecosystem prevents drought and floods

Answer: c
Clarification: Ecological services are said to be the products of ecosystem processes. They are the base for economic, environmental, and aesthetic goods and services for a healthy ecosystem. The forest ecosystem is essential for the survival of species.

250+ TOP MCQs on Environmental Issues – Greenhouse Effect and Global Warming and Answers

Biology Multiple Choice Questions on “Environmental Issues – Greenhouse Effect and Global Warming”.

1. From which phenomenon is the term ‘Greenhouse effect’ derived?
a) That occurs in a boathouse
b) That occurs in a greenhouse
c) That occurs in a blue house
d) That occurs in a house
Answer: b
Clarification: A greenhouse, also called a glasshouse is a building made of transparent material, in which plants such as flowers and vegetables requiring regulated climatic conditions are grown. The word greenhouse gives rise to the term ‘Greenhouse effect’.

2. What is a small glasshouse used for growing plants especially during winter called?
a) Greenhouse
b) Lakehouse
c) Boathouse
d) Treehouse
Answer: a
Clarification: A building made of transparent material, in which plants requiring regulated climatic conditions are grown is called a greenhouse. In this, the plants are grown especially during winters.

3. In a greenhouse the glass panel lets the light in, but what is not escaped?
a) Light
b) Heat
c) Energy
d) Air
Answer: b
Clarification: A greenhouse is a building made of transparent material in which plants requiring regulated climatic conditions are grown. It has a glass panel that allows the entry of light but does not allow the departure of light.

4. What helps in warming the greenhouse?
a) Light
b) Energy
c) Plants
d) Heat
Answer: d
Clarification: The plants such as flowers and vegetables requiring regulated climatic conditions are grown in a greenhouse that is made up of transparent material. The heat is not allowed to escape out from the greenhouse that warms the internal environment.

5. Which naturally occurring phenomenon is responsible for heating of Earth’s surface and atmosphere?
a) Eutrophication
b) Bio-magnification
c) Greenhouse effect
d) Cooking
Answer: c
Clarification: The naturally occurring phenomenon is responsible for heating of Earth’s surface and atmosphere due to the radiation from a planet’s atmosphere is called the greenhouse effect. It makes the atmosphere of Earth comfortable to live.

6. Which gases are commonly known as greenhouse gases?
a) Nitrogen
b) Carbon dioxide
c) Chlorine
d) Oxygen
Answer: b
Clarification: The gases that lead to the heating of Earth’s surface and atmosphere due to the radiation from a planet’s atmosphere are known as greenhouse gases. They are responsible for the greenhouse effect. Some gases such as carbon dioxide, methane, nitrous oxide, etc.

7. The given diagram shows the contribution of greenhouse gases. Which gas contributes maximum to the greenhouse effect?

a) Methane
b) CFC
c) Nitrous oxide
d) Carbon dioxide
Answer: d
Clarification: The gases that lead to the heating of Earth’s surface and atmosphere due to the radiation from a planet’s atmosphere are known as greenhouse gases. They are responsible for the greenhouse effect. According to the given diagram, carbon dioxide contributes maximum to the greenhouse effect.

8. The given diagram shows the contribution of greenhouse gases. Which gas contributes a minimum to the greenhouse effect?

a) Methane
b) CFC
c) Nitrous oxide
d) Carbon dioxide
Answer: c
Clarification: The greenhouse gases are those that lead to the heating of Earth’s surface and atmosphere due to the radiation from a planet’s atmosphere and are responsible for the greenhouse effect. According to the given diagram, nitrous oxide contributes a minimum to the greenhouse effect.

9. What does the increase in the level of greenhouse gases lead to?
a) No change in ecosystem cycles
b) Proper plant growth
c) Proper rainfall
d) Global warming
Answer: d
Clarification: Global warming is the phenomenon occurring due to an increase in the level of greenhouse gases. This leads to considerable heating and an increase in temperature of Earth leading to deleterious changes in the environment. This causes odd climatic changes.

10. Which one of the following ways can be used to control global warming?
a) Increasing deforestation
b) Reducing efficiency of energy usage
c) Reducing the use of fossil fuel
d) Increasing the growth of human population
Answer: c
Clarification: The phenomenon occurring due to an increase in the level of greenhouse gases is known as global warming. This leads to an increase in Earth’s temperature and leading to deleterious changes in the environment. This can be controlled by reducing the use of fossil fuels.

11. Which one of the following ways can be used to control global warming?
a) Increasing the growth of human population
b) Planting trees
c) Increasing the use of fossil fuel
d) Increasing deforestation
Answer: b
Clarification: The increase in temperature of Earth due to an increase in the level of greenhouse gases is known as global warming. This leads to various changes in the environment. This can be controlled by planting trees and afforestation.

250+ TOP MCQs on Organisms – Sexual Reproduction and Answers

Biology Multiple Choice Questions on “Organisms – Sexual Reproduction”.

1. What is sexual reproduction?
a) Fusion of male and female gamete
b) Fusion of male and male gamete
c) Fusion of female and female gamete
d) Either a male or a female gamete

Answer: a
Clarification: The fusion of a haploid male (23 chromosomes) and a haploid female gamete (23 chromosomes) produces a diploid (46 chromosomes) egg or a zygote. This process of reproduction is known as sexual reproduction.

2. What is phase when the organism is old enough to reproduce known as?
a) Juvenile phase
b) Vegetative phase
c) Senescence
d) Reproductive phase

Answer: d
Clarification: The phase when it is growing is known as the juvenile phase or the vegetative phase (in plants). The phase after that when the reproductive organs in the organism matures is known as the reproductive phase. Senescence is the phase when the plant starts deteriorating as it grows old and finally dies.

3. In which plant species is it difficult to define the different phases (juvenile, reproductive phase)?
a) Biennial
b) Annual
c) Perennial
d) Seasonal

Answer: c
Clarification: It is difficult to clearly distinguish between the different phases in perennial plants. Some plants exhibit unusual flowering phenomena. Some plants flower every year, there are some that flower every 10 years and some plants flower every 50 years. Neelakurinji is a flowering plant that flowers every 12 years.

4. Which type of plants flower only once?
a) Monocarpic
b) Polycarpic
c) Vivipary
d) Unocarpic

Answer: a
Clarification: Monocarpic plants flower only once in its lifetime. They die after flowering. Annuals like marigold, wheat, paddy, biennials like radish, perennials like Bambusa tulda which flowers every 50-100 years, fruits and dies.

5. Which type of plant flowers repeatedly?
a) Polypary
b) Vivipary
c) Polycarpic
d) Monocarpic

Answer: c
Clarification: Polycarpic plants are those that flower repeatedly, which means they do not die after flowering once. Examples are perennials like apple, mango and perennial flowers like china rose, it flowers throughout the year.

6. What are the 3 phases in a life cycle (in order)?
a) reproductive, senescence, juvenile
b) juvenile, senescence, death
c) reproductive, senescence, death
d) juvenile, reproductive, senescence

Answer: d
Clarification: There are 3 phases in a life cycle.
i. Juvenile phase/ vegetative phase: period from birth to maturation of reproductive systems.
ii. Reproductive phase: period when the reproductive systems have matured and ready to produce offspring.
iii. Senescence: period when the organism starts growing old and starts degrading.

7. Name the sequence in which sexual reproduction is divided into?
a) fertilization, post-fertilization, reproduction
b) pre-fertilization, fertilization, post-fertilization
c) pre-fertilization, fertilization, reproduction
d) pre-fertilization, post-fertilization, fertilization

Answer: b
Clarification: Sexual reproduction is the fusion of the male and the female gamete that forms a single celled zygote, the process is known as fertilization. This process has been divided into 3 events. The pre-fertilization, fertilization and post-fertilization events.

8. Which factor is responsible for the changes in the 3 phases in a life cycle?
a) Blood
b) Hormones
c) Respiration
d) Nervous system (in animals)

Answer: b
Clarification: Hormones are chemical messengers that travel through the bloodstream (in case of animals). Hormones are responsible for the change in the phases in both plants and animals. Hormonal change can be affected by environmental factors too.

9. What process does the image show?

a) Parthenogenesis
b) Fertilization
c) Torrulation
d) Sporolation

Answer: b
Clarification: Fertilization is the process of fusion of the male and female gamete to form an egg or a zygote. It is a type of sexual reproduction. Formation of a diploid cell from 2 haploid cells.

10. Sexual reproduction is a fast process.
a) False
b) True

Answer: a
Clarification: Sexual reproduction, unlike asexual reproduction is a slow process. Since it is the fusion of 2 opposite sex gametes, it produces variations better than the parent. The time period varies from specie to specie.

250+ TOP MCQs on Flowering Plants Reproduction – Double Fertilisation and Answers

Biology Multiple Choice Questions on “Flowering Plants Reproduction – Double Fertilisation”.

1. Double fertilization is seen in _______
a) angiosperms
b) gymnosperms
c) Malaceae
d) Viola
Answer: a
Clarification: Double fertilization is found in angiosperms only. In angiosperms, female gametophyte abruptly stops its growth at 8 nucleate stages. After the formation of the zygote and primary endosperm nucleus, further growth of embryo sac takes place.

2. In _______, female gametophytes stop their growth at 8 nucleate stages.
a) cleistogamous
b) chasmogamous
c) gymnosperms
d) angiosperms
Answer: d
Clarification: Double fertilization occurs only in angiosperms. The female gametophyte in angiosperms abruptly stop their growth at 8 nucleate stages.

3. The further growth of embryo takes place when the ______ has been formed.
a) pollen
b) ovule
c) zygote
d) pistil
Answer: c
Clarification: Further growth of embryo sac occurs only when the zygote has been formed and primary endosperm nucleus has been created by triple fusion.

4. What initiates the formation of endosperms?
a) Fertilization
b) Triple fusion
c) Fusion
d) Double fusion
Answer: b
Clarification: The triple fusion initiates the formation of endosperm by withdrawal of nourishment from the nucellus and parent plant.

5. Endosperm is formed only when it is needed.
a) True
b) False
Answer: a
Clarification: The need arises after fertilization because the endosperm provides nutrition for the simultaneously developing embryo. If fertilization fails, no endosperm will be formed.

6. Which 2 scientists stated that endosperms were for reduction of female gametophyte?
a) Chargaff and Franklin
b) Nirenburg and Khoranna
c) Watson and Crick
d) Brink and Cooper
Answer: d
Clarification: According to Brink and Cooper (1940), endosperm is a tissue developed to compensate for the extreme reduction of female gametophyte in angiosperms.

7. The growth of the pollen tube is directed by ______
a) obturator
b) meristem
c) parenchyma
d) schlerenchyma
Answer: a
Clarification: In the ovary the growth of the pollen tube is directed by another tissue called obturator. The pollen tube enters the ovule, either through its micropyle (porogamy e.g., Lily), chalaza (chalazogamy e.g., Betula, Casuarina, Juglans regia) or the sides after piercing through the integuments (mesogamy, e.g. Cucurbita, Populus, Pistacea).

8. Generative fertilization is also called _____
a) apomixis
b) syngamy
c) vegetative fertilization
d) senescence
Answer: b
Clarification: Generative fertilization is also called syngamy or true fertilization. Out of the two male gametes one fuses with egg or oosphere to perform generative fertilization.

9. Second fertilization is called ________
a) syngamy
b) apomixis
c) senescence
d) vegetative fertilization
Answer: d
Clarification: Second fertilization is called vegetative fertilization since as a consequence, a vegetative or nutritive tissue is formed to nourish the embryo. Vegetative fertilization is also called triple fusion since three nuclei get fused, two polar nuclei and one male gamete.

10. Pollen tube is attracted to the _____ end of the embryo sac.
a) micropylar
b) hilum
c) synergid
d) generative
Answer: a
Clarification: After entering the ovule, the pollen tube is attracted towards the micropylar end of the embryo sac. The attractants are secreted by synergids or help cells. The pollen tube pierces one of the two synergids and bursts open into it.

250+ TOP MCQs on Human Reproduction – Menstrual Cycle and Answers

Biology Quiz on “Human Reproduction – Menstrual Cycle – 2”.

1. The regeneration of uterine wall begins during what phase?
a) Menstrual phase
b) Follicular phase
c) Luteal phase
d) Secretory phase
Answer: b
Clarification: The menstrual phase involves shredding of the uterine endometrium. Right after menses, the follicular phase onsets. During this phase, the endometrium starts to regenerate.

2. What pituitary hormones peak during the proliferative phase?
a) LH only
b) FSH only
c) Neither LH or FSH
d) LH and FSH
Answer: d
Clarification: The anterior pituitary releases Luteinizing Hormone and Follicle Stimulating Hormone as the proliferative phase or follicular phase progresses. Both of these hormones along with the ovarian hormone estrogen is responsible for the regeneration of uterine wall and maturation of follicles.

3. Which of the following does not occur during the follicular phase?
a) Maturation of primary follicles to Graafian follicles
b) Peaking of estrogen
c) Peaking of progesterone
d) Regeneration of uterine endometrium
Answer: c
Clarification: Follicular phase is an important phase to ensure the development of egg and maturation of the follicle it is contained in. It is also characterized by the thickening of uterine wall. These changes are brought about the pituitary hormones LH and FSH and the ovarian hormone estrogen. Progesterone is required for egg release and it peaks during the luteal phase.

4. The luteal phase is also called as ______
a) secretory phase
b) proliferative phase
c) menstrual phase
d) follicular phase
Answer: a
Clarification: Luteal phase involves the rupture of the Graafian follicle and the release of egg from the ovary. Hence it is also called the secretory phase.

5. A student was studying primate uterine thickness. She had 3 samples of uterine tissues. The thickness in mm for the samples are as follows:
Sample A – 4 mm, Sample B – 10 mm, Sample C – 1 mm
Given the knowledge of menstrual cycle in humans, what phases do you think each sample belongs to?
a) Sample A: Menstrual phase, Sample B: Follicular phase, Sample C: Luteal phase
b) Sample A: Proliferative phase, Sample B: Luteal phase, Sample C: Menstrual phase
c) Sample A: Secretory phase, Sample B: Menstrual phase, Sample C: Proliferative phase
d) Sample A: Menstrual phase, Sample B: Secretory phase, Sample C: Follicular phase
Answer: b
Clarification: The uterine endometrium is shed off during menstrual phase. Thus this wall has the least thickness. During the follicular or proliferative phase, the endometrium starts building up and the wall is completely thick during the luteal or secretory phase to house the expected fertilized egg.

6. Which hormone surge triggers ovulation?
a) Estrogen
b) LH
c) FSH
d) Progesterone
Answer: b
Clarification: LH is released by the anterior pituitary. It reaches a peak level during the middle of menstrual cycle. This is called LH surge. It acts on Graafian follicles causing their rupture and release of egg in the process of ovulation.

7. Luteal phase is characterized by the conversion of a ruptured Graafian follicle into _______
a) corpus luteum
b) corpus albicans
c) corpora quadrigemina
d) primary follicle
Answer: a
Clarification: During the luteal or secretory phase, the Graafian follicle is ruptured and the egg is released from the ovum into the fallopian tube to encounter the sperm. The empty Graafian follicle gets filled with the external theca and granulosa cells. This is the onset of degeneration of Graafian follicle and is called the corpus luteum.

8. What hormone is responsible for the maintenance of endometrium?
a) Estrogen
b) LH
c) FSH
d) Progesterone
Answer: d
Clarification: Progesterone is secreted by the corpus luteum. It is responsible for proper maintenance of the embryo so that if an egg is fertilized, the developing embryo can get a proper attachment and doesn’t exit through vagina.

9. What part of ovary secretes progesterone?
a) Medulla
b) Epithelial covering
c) Graafian follicle
d) Corpeus luteum
Answer: d
Clarification: Corpeus luteum is formed by the degeneration of Graafian follicle after it releases an egg. This degenerating tissue releases progesterone to maintain the proper function and structure of endometrium.

10. What is the fate of corpus luteum in case of unfertilized egg?
a) Rapid proliferation
b) Degeneration
c) Secretion of progesterone
d) Onset of next menstrual cycle
Answer: b
Clarification: Corpus luteum releases progesterone to support endometrium required for homing the embryo. But if the egg is not fertilized, the endometrium is useless and should be released off to save energy. Thus corpus luteum is degraded.

11. The end of menstrual cycle is called _______
a) Menarche
b) Menopause
c) Menses
d) Ovulation
Answer: b
Clarification: Menopause in humans occurs at an age of approximately 55 years. This is the last menstrual cycle. Thus the normal reproductive phase lasts between menarche and menopause.

12. Which hormone elevates twice during a menstrual cycle?
a) LH
b) FSH
c) Estrogen
d) Progesterone
Answer: c
Clarification: LH and FSH peak during the middle of the menstrual cycle. Progesterone peaks after release of egg due to formation of corpus luteum. Estrogen peaks twice. First during the ovulation and second prior to menstruation.

Biology for Quizzes,